1. Technical Field
The present invention relates to a projector, an information storing medium, and a trapezoidal distortion correcting method.
2. Related Art
As a trapezoidal distortion correcting method employed in a projector (trapezoidal distortion correction is also called, for example, trapezoidal correction and keystone correction), for example, JP-A-2005-229293 proposes a correcting method in which a plurality of phase difference sensors is used to measure the distances to a plurality of measurement points on an object on which an image is projected, and JP-A-2005-347790 proposes a correcting method in which an image sensor is used to capture an image and acquires information on the peripheral boundary lines of an object on which an image is projected.
In the distance measuring method, however, since the measurement precision decreases when the distance to the object on which an image is projected increases, the projector cannot correct a trapezoidal distortion accurately. On the other hand, in the method carried out by acquiring information on the peripheral boundary lines or the shape of the object on which an image is projected, the projector cannot correct a trapezoidal distortion accurately because part of the captured image includes no boundary line when the distance to the object on which an image is projected decreases.